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Search: id:A128978
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A128978 a(1) = 1, a(2) = 1 and a(n) = number of terms among (a(1),a(2),...a(n-1)) which divide (a(n-1)+a(n-2)). +0
1
1, 2, 1, 2, 2, 5, 2, 2, 7, 2, 2, 9, 2, 2, 11, 2, 2, 13, 3, 13, 13, 16, 2, 16, 16, 17, 4, 4, 16, 17, 4, 4, 18, 15, 4, 2, 16, 18, 17, 4, 4, 22, 18, 23, 2, 3, 3, 19, 18, 2, 25, 6, 2, 25, 6, 2, 26, 27, 2, 2, 28, 28, 31, 2, 6, 29, 4, 6, 23, 3, 26, 3, 3, 32, 4, 46, 25, 2, 10, 42, 37, 2, 11, 5, 38, 2 (list; graph; listen)
OFFSET

1,2

COMMENT

a(n} = 2 for n's: 2, 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 23, 36, 45, 50, 53, 56, 59, 60, 64, 78, 82, 86, ....

First occurrence of k: 1, 2, 19, 27, 6, 52, 9, 186, 12, 79, 15, 255, 18, 107, 34, 22, 26, 33, 48, 134, 205, 42, 44, 381, 51, ....

LINKS

Leroy Quet, Home Page (listed in lieu of email address)

MATHEMATICA

f[s_List] := Block[{}, Append[s, Count[ Mod[ s[[ -1]] + s[[ -2]], s], 0]]]; Nest[f, {1, 2}, 85] (* Robert G. Wilson v *)

CROSSREFS

Cf. A128923.

Sequence in context: A089408 A079318 A050315 this_sequence A145862 A058701 A004559

Adjacent sequences: A128975 A128976 A128977 this_sequence A128979 A128980 A128981

KEYWORD

nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com) and Leroy Quet Apr 29 2007

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Last modified November 24 14:25 EST 2009. Contains 167438 sequences.


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